PUVA Therapy is recognized as an effective mode in treating psoriasis. It has no known anti-rheumatic properties. Approximately 15% of patients with psoriasis have an associated arthritis. This study monitors arthritis activity in patients with psoriatic arthritis during the course of PUVA Therapy, and correlates it with skin response to PUVA. Data show two subpopulations of patients with arthritis: those with peripheral joint and those with axial involvement. The former group demonstrates a positive correlation between skin responsiveness and joint responsiveness. The latter group does not. The latter group has sacroiliitis and appears refractory to most forms of anti-inflammatory medication.